Mtani the retriever and Kasi the cheetah met over one year ago at Busch Gardens theme park in Tampa, Florida. Both animals were only a few months old when they were introduced. The unlikely couple spent their earliest days together, discovering how to communicate and play with one another.

Despite the odds, there are countless stories of the most unlikely cross-species relationships imaginable: a goat guiding a blind horse; a doe who regularly visits her Great Dane surrogate mother; a juvenile gibbon choosing to live with a family of capuchins, and so on. Instincts gone awry? The subject has mystified scientists for years. Now, NATURE investigates why animals form these special bonds.

Wild! Lions Behaving Badly (9:00 pm)

Wild! Lions Behaving Badly

Instead of ambushing their prey and quickly dispatching with a clean bite to the throat, these lions wrestle their victim to the ground and tuck in before the hapless beast is dead, meaning a slow and painful death. Are these lions behaving badly, or is it simply that this is what lions do?

Wild Australasia: Gum Tree Country (10:00 pm)

Gang-gang cockatoos are found in the highland forests of south-eastern Australia.They feast on young eucalypt seed capsules or gum nuts, which they crack open with their strong beaks.

It's a classic landscape - the great Australian Bush. Vast swathes of land, dominated by eucalypts, or gum trees, have become one of the most enduring symbols of the continent. But the bushland of Crocodile Dundee and Ned Kelly fame has other faces. In Gum Tree Country we take you on a journey 'out bush', from the shimmering heat of the north, through icy, snowbound woodlands, and misty forests where the tallest hardwood trees in the world grow to well over 100 meters. And in all these places, strange animals live...